Glucose transporter gene expression in bovine mammary gland

Transport of glucose across the plasma membrane of mammary epithelial cells is believed to be a passive process of facilitated diffusion mediated by,f acilitative glucose transporter(s). This article presents three lines of ev idence that indicate the expression of sodium/glucose cotransporter (SGLT1) in the mammary gland of lactating and nonlactating cows. First, transcript s of SGLT1 mRNA ranging in size from 1.5 to 5.2 kb were detected in polyade nylated RNA preparations of mammary glands of lactating and nonlactating co ws. Second, SGLT1 cotransporter protein was also detected in plasma membran e preparations of mammary glands of lactating cows. Third, partial amino ac id sequence deduced from the reverse transcriptase-PCR fragment of SGLT1 fr om bovine mammary glands was similar to the sequence reported for ovine SGL T1. We conclude that mammary gland expression of SGLT1 mRNA and protein sug gests that an active glucose transport system may be involved in glucose tr ansport and metabolism in the mammary gland of dairy cows. However, the phy siological significance of the expression of SGLT1 in mammary gland remains unknown.